Discovery News (January 25, 2010)
"After the dinosaurs went extinct, the ancestors of some flightless birds didn't bother leaving the ground."
"The flighted ancestor of birds such as the Australian emu and cassowary became too heavy to fly after the extinction of dinosaurs made it safer to forage for food, suggests a new study.
"The finding by Australian National University (ANU) biologist Dr Matthew Phillips and colleagues at Massey University in New Zealand also answers the mystery of how flightless birds managed to disperse across oceans.
"Their work, published in the latest Systematic Biology journal, follows on from recent work that raised uncertainty about the "single ancestor" theory of the group of flightless birds, known as ratites.
"Phillips, of the ANU's Research School of Biology, says ratites are a group of flightless birds that include the Australian emu and cassowary, African ostrich, New Zealand's kiwi and now-extinct moa, rhea from South America and the extinct elephant birds of Madagascar...."
Scientists have figured that all of today's flightless birds came from a single ancestor, which lived long before the dinosaurs went extinct about 65,000,000 years ago. The idea was that they walked across the supercontinent that existed before the current round of continental drifting.
Good idea, plausible - except that the supercontinent broke up before that ancestral bird.
Now, it looks like the flightless birds weren't, until more recently. Probably around the dinosaurs went extinct, making room for big animals on the ground.
The Discovery News article discusses research - mostly using mitochondrial DNA.
Interesting - for me, anyway. I remember when paleontology was mostly a matter of digging fossilized bones out of rocks and piecing them together.
- "Bringing Back the Dinosaurs: Not a Crazy Idea Any More"
(June 29, 2009)